JP2018065069A - Adsorbent and process for producing the same, method for removing carbon dioxide, and air conditioning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing an adsorbent that can increase the adsorption amount of carbon dioxide more than before.SOLUTION: Provided is a process for producing an adsorbent used for removing carbon dioxide from a carbon dioxide-containing gas to be treated, and said process including a first step of producing a first product by reacting cerium salt, hydrogen peroxide and ammonia, a second step of producing a second product by reacting the first product and an acid component, and a third step of reacting the second product and a basic component.SELECTED DRAWING: None

Description

  The present invention relates to an adsorbent and a method for producing the same, a method for removing carbon dioxide, and an air conditioner.

In recent years, global warming due to greenhouse gas emissions has become a global problem. Examples of the greenhouse gas include carbon dioxide (CO ₂ ), methane (CH ₄ ), and chlorofluorocarbons (CFCs and the like). Among the greenhouse gases, carbon dioxide has the greatest influence, and construction of a method for removing carbon dioxide (for example, carbon dioxide discharged from thermal power plants, steelworks, etc.) is required.

Carbon dioxide is known to affect the human body. For example, when a gas containing carbon dioxide at a high concentration is sucked, drowsiness, health damage and the like are caused. In spaces with high human density (buildings, vehicles, etc.), the concentration of carbon dioxide in the room (hereinafter referred to as “CO ₂ concentration” in some cases) is likely to increase due to human expiration, and the CO ₂ concentration is adjusted by ventilation. There is a case.

In order to quickly ventilate indoor air and outside air, it is necessary to operate a blower such as a blower. Moreover, since the temperature and humidity of the air taken in from the outside (outside air) are not adjusted, it is necessary to operate the cooling in the summer and to operate the heating in the winter. For these reasons, an increase in indoor CO ₂ concentration is a factor in increasing power consumption associated with air conditioning.

The amount of reduction of carbon dioxide in the room due to ventilation (CO ₂ reduction amount) is expressed by the following equation. In the following equation, the CO ₂ concentration can be kept constant if the amount of CO ₂ decrease on the left side is equivalent to the amount of CO ₂ increase due to human expiration.
CO ₂ reduction amount = (CO ₂ concentration in the chamber - external air CO ₂ concentration) × ventilation

However, in recent years, since the CO ₂ concentration in the outside air has increased, the difference in CO ₂ concentration from the room has become smaller. For this reason, the amount of ventilation required to adjust the CO ₂ concentration is also increasing. In the future, when the CO ₂ concentration in the outside air further increases, it is considered that the power consumption increases by adjusting the CO ₂ concentration by ventilation.

  The said subject arises by ventilation with external air. Therefore, if carbon dioxide can be selectively removed using a method other than ventilation, the amount of ventilation can be reduced, and as a result, power consumption associated with air conditioning may be reduced.

  Also, in spaces (air stations, submersibles, etc.) shielded from the outside air in which air exists, it is difficult to ventilate the outside air and room air, so it is necessary to selectively remove carbon dioxide by methods other than ventilation. There is.

Examples of a solution to the problem include a method of removing carbon dioxide by a chemical absorption method, a physical absorption method, a membrane separation method, an adsorption separation method, a cryogenic separation method, or the like. For example, a method of separating and recovering carbon dioxide using a CO ₂ adsorbent (hereinafter simply referred to as “adsorbent”) (CO ₂ separation and recovery method) can be mentioned. For example, zeolite is known as an adsorbent (see, for example, Patent Document 1 below).

JP 2000-140549 A

  By the way, with respect to a carbon dioxide removal method using an adsorbent, it is required to improve the amount of carbon dioxide adsorbed on the adsorbent from the viewpoint of improving the carbon dioxide removal efficiency.

  This invention is made | formed in view of the said situation, and it aims at providing the adsorption agent which can improve the adsorption amount of a carbon dioxide rather than before, and its manufacturing method. Another object of the present invention is to provide a carbon dioxide removal method and an air conditioner using the adsorbent.

  The method for producing an adsorbent according to the present invention is a method for producing an adsorbent used for removing carbon dioxide from a gas to be treated (gas to be treated) containing carbon dioxide, comprising a cerium salt, A first step of reacting hydrogen peroxide and ammonia to obtain a first product; a second step of reacting the first product and an acid component to obtain a second product; And a third step of reacting the second product with the base component.

According to the method for producing an adsorbent according to the present invention, an adsorbent capable of improving the amount of carbon dioxide adsorbed than before can be obtained. Such an adsorbent is superior in CO ₂ adsorbability (carbon dioxide adsorbability, carbon dioxide scavenging ability) than before.

By the way, in the method using a conventional adsorbent such as zeolite, when the CO ₂ concentration of the gas to be treated is low, the carbon dioxide removal efficiency tends to decrease. On the other hand, according to the present invention, when the CO ₂ concentration of the gas to be treated is low, the amount of carbon dioxide adsorbed on the adsorbent can be improved as compared with the conventional case. According to the present invention, carbon dioxide can be removed more efficiently than before when the CO ₂ concentration of the gas to be processed is low.

  The cerium salt preferably contains at least one selected from the group consisting of cerium oxalate and cerium nitrate. In this case, the adsorption amount of carbon dioxide can be further improved.

  The acid component preferably includes nitric acid. In this case, the adsorption amount of carbon dioxide can be further improved.

  The base component preferably contains ammonia. In this case, the adsorption amount of carbon dioxide can be further improved.

  The method for producing an adsorbent according to the present invention preferably further includes a heating step of heating the first product between the first step and the second step. In this case, the adsorption amount of carbon dioxide can be further improved.

  The heating temperature in the heating step is preferably 70 ° C. or higher. In this case, the adsorption amount of carbon dioxide can be further improved.

  The adsorbent according to the present invention is an adsorbent obtained by the above-described adsorbent production method.

  The method for removing carbon dioxide according to the present invention comprises contacting the adsorbent obtained by the above-described adsorbent manufacturing method or the above-mentioned adsorbent with a gas to be treated containing carbon dioxide, and using the carbon dioxide as the adsorbent. A step of adsorbing. According to the method for removing carbon dioxide according to the present invention, the amount of carbon dioxide adsorbed on the adsorbent can be improved as compared with the conventional method, and the carbon dioxide removal efficiency can be improved.

  An air conditioner according to the present invention is an air conditioner used in an air conditioning target space including a processing target gas containing carbon dioxide, and includes a flow path connected to the air conditioning target space, and carbon dioxide contained in the processing target gas. Is removed in the flow path, and the adsorbent obtained by the adsorbent manufacturing method described above or the adsorbent described above is disposed in the remover, and the adsorbent contacts the gas to be processed. Carbon dioxide is adsorbed on the adsorbent. According to the air conditioner according to the present invention, the amount of carbon dioxide adsorbed on the adsorbent can be improved as compared with the conventional case, and the carbon dioxide removal efficiency can be improved.

The CO ₂ concentration of the processing object gas may be 5000 ppm or less, or 1000 ppm or less.

ADVANTAGE OF THE INVENTION According to this invention, the adsorption amount of the carbon dioxide with respect to adsorption agent can be improved rather than before. In particular, according to the present invention, when the CO ₂ concentration of the gas to be treated is low, the amount of carbon dioxide adsorbed on the adsorbent can be improved as compared with the conventional case.

FIG. 1 is a schematic diagram showing an air conditioner according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an air conditioning system according to an embodiment of the present invention.

  In this specification, the numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present specification, the upper limit value or lower limit value of a numerical range of a certain step may be replaced with the upper limit value or lower limit value of the numerical range of another step. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. It is. The materials exemplified in the present specification can be used singly or in combination of two or more unless otherwise specified. In the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. Means.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

<Method for producing adsorbent>
The method for producing an adsorbent according to this embodiment is a method for producing an adsorbent used for removing (for example, recovering) carbon dioxide from a gas to be treated containing carbon dioxide. The adsorbent manufacturing method according to the present embodiment includes a first step (chemical oxidation step) in which a cerium salt, hydrogen peroxide, and ammonia are reacted to obtain a first product, and the first generation. A second step (dispersing step) for obtaining a second product by reacting a product with an acid component, and a third step (reaggregation step / acid component for reacting the second product with a base component) Removing step).

According to the method for producing an adsorbent according to the present embodiment, an adsorbent having excellent CO ₂ adsorption is obtained. The cause of this is not clear, but the present inventors presume that it is as follows. In the method for producing an adsorbent according to the present embodiment, after reacting the first product (ceria or the like) and the acid component in the second step, the second product and the base component in the third step. Is allowed to react to obtain an adsorbent having a surface state suitable for carbon dioxide adsorption. From the above, it is speculated that an adsorbent having excellent CO ₂ adsorptivity can be obtained. According to the method for producing an adsorbent according to the present embodiment, it is possible to obtain an adsorbent without performing a high-temperature treatment (for example, 150 ° C. or higher), and therefore an adsorption having a specific surface area suitable for carbon dioxide adsorption. An agent can be obtained. According to the method for producing an adsorbent according to the present embodiment, an adsorbent having excellent CO ₂ adsorbability can be obtained particularly when the CO ₂ concentration of the gas to be treated is low.

  The cerium salt in the first step preferably contains at least one selected from the group consisting of cerium oxalate and cerium nitrate. Examples of cerium oxalate include cerium oxalate and cerium oxalate hydrate. Examples of cerium oxalate hydrate include cerium oxalate nonahydrate. Examples of cerium nitrate include cerium nitrate and cerium nitrate hydrate. Examples of cerium nitrate hydrate include cerium nitrate hexahydrate. Cerium oxalate can be obtained by reacting cerium nitrate with oxalic acid.

  The amount of hydrogen peroxide used in the first step is preferably 25 parts by mass or more, more preferably 100 parts by mass or more, with respect to 100 parts by mass of cerium salt, from the viewpoint of further improving the amount of adsorption of carbon dioxide. More preferably, it is more preferably 500 parts by mass or more. The amount of hydrogen peroxide used is preferably 1000 parts by mass or less with respect to 100 parts by mass of the cerium salt from the viewpoint of further improving the amount of carbon dioxide adsorbed.

  The amount of ammonia used in the first step is preferably 15 parts by mass or more, more preferably 100 parts by mass or more, and 120 parts by mass with respect to 100 parts by mass of the cerium salt from the viewpoint of further improving the amount of carbon dioxide adsorbed. The above is more preferable, and 300 parts by mass or more is particularly preferable. The amount of ammonia used is preferably 1000 parts by mass or less based on 100 parts by mass of the cerium salt from the viewpoint of further improving the amount of carbon dioxide adsorbed.

  As the acid component in the second step, a strong acid (for example, an acid having a pKa value (pKa1) of the first dissociable acid group of 0 or less) can be used. Examples of the strong acid include nitric acid, sulfuric acid, hydrochloric acid and the like, and nitric acid is preferable. Examples of the base component in the third step include ammonia and sodium hydroxide. Among them, ammonia is preferable. In the second step, ultrasonic treatment (ultrasonic irradiation) may be performed, or heat treatment may be performed.

  It is preferable that the manufacturing method of the adsorbent according to the present embodiment further includes a heating step of heating the first product between the first step and the second step. Thereby, it is possible to decompose the hydrogen peroxide used in the first step, and the adsorbent is obtained by the action of hydrogen peroxide in the presence of the acid component in the second step to reduce cerium. It can suppress that the surface area of this falls. In the heating step, foaming from the first product may be confirmed. It is thought that foaming occurs when oxygen is generated as hydrogen peroxide decomposes.

The heating temperature in the heating step is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, from the viewpoint that hydrogen peroxide can be easily decomposed to easily obtain an adsorbent with further excellent CO ₂ adsorption. The heating temperature is preferably 100 ° C. or less from the viewpoint of easily preventing the surface state of the first product from changing due to volatilization of moisture.

  The heating time in the heating step may be, for example, 10 minutes or longer. The heating time may be, for example, 10 hours or less, 3 hours or less, or 1 hour or less.

<Adsorbent>
The adsorbent according to the present embodiment is an adsorbent obtained by the above-described adsorbent manufacturing method. The adsorbent (carbon dioxide scavenger) according to the present embodiment is used to remove carbon dioxide from a processing target gas containing carbon dioxide.

The adsorbent according to the present embodiment can contain cerium oxide (cerium oxide). Examples of the cerium oxide include CeO _x (x = 1.5 to 2.0), and specific examples include CeO ₂ and Ce ₂ O ₃ .

  The adsorbent may be chemically treated, and may have a high specific surface area, for example, by mixing a filler (alumina, silica, etc.) as a binder.

  The content of cerium oxide in the adsorbent may be 30% by mass or more, 70% by mass or more, or 90% by mass or more based on the total mass of the adsorbent. The adsorbent may be an embodiment made of cerium oxide (an embodiment in which the content of cerium oxide is substantially 100% by mass based on the total mass of the adsorbent). The greater the content of cerium oxide, the more the carbon dioxide adsorption can be improved. The content of cerium oxide can be adjusted by, for example, the content of cerium oxalate in the raw material.

Examples of the shape of the adsorbent include powder, pellets, granules, and honeycombs. The shape of the adsorbent may be determined in consideration of the required reaction rate, pressure loss, adsorption amount of the adsorbent, purity of the gas (adsorbed gas) adsorbed on the adsorbent (CO ₂ purity), and the like. The shape of the adsorbent may be the same as the shape of the raw material.

<Method for removing carbon dioxide>
The carbon dioxide removal method according to the present embodiment includes an adsorption process in which the adsorbent according to the present embodiment is brought into contact with a processing target gas containing carbon dioxide to adsorb carbon dioxide to the adsorbent.

The CO ₂ concentration in the processing target gas may be 5000 ppm or less (0.5% by volume or less) based on the total volume of the processing target gas. According to the carbon dioxide removal method according to the present embodiment, carbon dioxide can be efficiently removed when the CO ₂ concentration is 5000 ppm or less. The reason why such an effect is achieved is not clear, but the present inventors speculate that it is as follows. In the adsorption step, carbon dioxide is not physically adsorbed on the surface of the cerium oxide, but carbon dioxide is considered to be adsorbed to the adsorbent by chemically bonding with the surface of the cerium oxide. In this case, in the carbon dioxide removal method according to the present embodiment, the partial pressure dependency of carbon dioxide in the adsorption to the adsorbent is small, and even if the CO ₂ concentration of the gas to be processed is 5000 ppm or less, the efficiency is higher than the conventional method. It is assumed that carbon dioxide can be removed.

CO ₂ concentration from the viewpoint of even if the CO ₂ concentration is low the effect of removing efficiently the carbon dioxide easily identified, based on the total volume of untreated gas may also be 2000ppm or less, 1500 ppm or less It may be 1000 ppm or less, 750 ppm or less, or 500 ppm or less. The CO ₂ concentration may be 100 ppm or more, 200 ppm or more, or 400 ppm or more on the basis of the total volume of the gas to be treated from the viewpoint of easily increasing the amount of carbon dioxide removed. From these viewpoints, the CO ₂ concentration may be 100 to 5000 ppm, 100 to 2000 ppm, 100 to 1500 ppm, or 100 to 1000 ppm, based on the total volume of the gas to be treated. It may be 200 to 1000 ppm, 400 to 1000 ppm, 400 to 750 ppm, or 400 to 500 ppm. In addition, the office hygiene standard rule of the Industrial Safety and Health Law stipulates that the indoor CO ₂ concentration should be adjusted to 5000 ppm or less. In addition, it is known that sleepiness is induced when the CO ₂ concentration exceeds 1000 ppm, and the building environmental hygiene management standard stipulates that the CO ₂ concentration should be adjusted to 1000 ppm or less. Therefore, the CO ₂ concentration may be adjusted by ventilating so that the CO ₂ concentration does not exceed 5000 ppm or 1000 ppm. The CO ₂ concentration in the gas to be treated is not limited to the above range, and may be 500 to 5000 ppm or 750 to 5000 ppm.

The gas to be treated is not particularly limited as long as it contains carbon dioxide, and may contain a gas component other than carbon dioxide. Examples of gas components other than carbon dioxide include water (water vapor, H ₂ O), oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), SOx, NOx, and volatile organic substances (VOC). It is done. Specific examples of the processing target gas include air in a room such as a building or a vehicle. In the adsorption step, when the gas to be treated contains water, carbon monoxide, SOx, NOx, volatile organic matter, etc., these gas components may be adsorbed by the adsorbent.

By the way, in the conventional adsorbents such as zeolite, when the gas to be treated contains water, the CO ₂ adsorptivity tends to be greatly reduced. Therefore, in order to improve the CO ₂ adsorptivity of the adsorbent in the conventional method using the adsorbent, it is necessary to perform a dehumidification step of removing moisture from the target gas before bringing the target gas into contact with the adsorbent. The dehumidifying step is performed using, for example, a dehumidifying device, which leads to an increase in equipment and an increase in energy consumption. On the other hand, the adsorbent according to the present embodiment has excellent CO ₂ adsorptivity compared to conventional adsorbents even when the gas to be treated contains water. Therefore, the carbon dioxide removal method according to the present embodiment does not require a dehumidification step, and carbon dioxide can be efficiently removed even when the gas to be treated contains water.

  The dew point of the gas to be processed may be 0 ° C. or higher. The relative humidity of the gas to be processed may be 30% or more, 50% or more, or 80% or more.

By adjusting the temperature T ₁ of the adsorbent at the time of contact with the adsorbent untreated gas in the adsorption process, it is possible to adjust the amount of adsorption of carbon dioxide. The higher the temperature T _{1, the} lower the amount of CO ₂ adsorbed by the adsorbent. Temperatures _{T 1} may be a -20 to 100 ° C., it may be 10 to 50 ° C..

Temperature T ₁ of the adsorbent may be adjusted by heating or cooling the adsorbent may be used in combination of heating and cooling. Further, the temperature T ₁ of the indirect adsorbent may be adjusted by heating or cooling the processed gas. As a method of heating the adsorbent, a method in which a heat medium (for example, heated gas or liquid) is brought into direct contact with the adsorbent; a heat medium (for example, heated gas or liquid) is circulated through a heat transfer tube, Examples include a method of heating the adsorbent by heat conduction from the heat transfer surface; a method of heating the adsorbent by an electric furnace that generates heat electrically, and the like. As a method for cooling the adsorbent, a method in which a refrigerant (for example, a cooled gas or liquid) is directly brought into contact with the adsorbent; a refrigerant (for example, a cooled gas or liquid) is circulated through a heat transfer tube or the like, and the heat transfer The method of cooling by the heat conduction from a surface etc. is mentioned.

In the adsorption step, the amount of carbon dioxide adsorbed can be adjusted by adjusting the total pressure of the atmosphere in which the adsorbent is present (for example, the total pressure in the container containing the adsorbent). As the total pressure is higher, the amount of CO ₂ adsorbed by the adsorbent tends to increase. From the viewpoint of further improving the carbon dioxide removal efficiency, the total pressure is preferably 0.1 atm or more, and more preferably 1 atm or more. The total pressure may be 10 atm or less, 2 atm or less, or 1.3 atm or less from the viewpoint of energy saving. The total pressure may be 5 atmospheres or more.

  The total pressure of the atmosphere in which the adsorbent is present may be adjusted by pressurization or depressurization, and pressurization and depressurization may be used in combination. Examples of a method for adjusting the total pressure include a method in which the pressure is mechanically adjusted by a pump, a compressor, and the like; a method in which a gas having a pressure different from the pressure in the ambient atmosphere of the adsorbent is introduced.

In the carbon dioxide removal method according to the present embodiment, the adsorbent may be supported on a honeycomb-shaped base material or may be used by filling the adsorbent into a container. The use method of the adsorbent may be determined in consideration of the required reaction rate, pressure loss, the amount of adsorbent adsorbed, the purity of the gas (adsorbed gas) adsorbed on the adsorbent (CO ₂ purity), and the like.

  When the adsorbent is filled in a container and used, the porosity is preferably as small as possible when increasing the purity of carbon dioxide in the adsorbed gas. In this case, since the amount of gas other than carbon dioxide remaining in the gap is reduced, the purity of carbon dioxide in the adsorbed gas can be increased. On the other hand, when reducing the pressure loss, it is preferable that the porosity is large.

  The carbon dioxide removal method according to the present embodiment may further include a desorption step of desorbing (desorbing) carbon dioxide from the adsorbent after the adsorption step.

  As a method for desorbing carbon dioxide from the adsorbent, a method using the temperature dependence of the adsorption amount (temperature swing method; a method utilizing the difference in the adsorption amount of the adsorbent with temperature change); Examples include a method of using (pressure swing method, a method of using a difference in the amount of adsorbent adsorbed due to pressure change) and the like, and these methods may be used in combination (temperature / pressure swing method).

  In the method using the temperature dependency of the adsorption amount, for example, the temperature of the adsorbent in the desorption process is set higher than that in the adsorption process. Examples of the method for heating the adsorbent include the same method as the method for heating the adsorbent in the above-described adsorption step; the method using the peripheral exhaust heat, and the like. From the viewpoint of reducing the energy required for heating, it is preferable to use the peripheral exhaust heat.

The temperature difference (T ₂ −T ₁ ) between the adsorbent temperature T ₁ in the adsorption step and the adsorbent temperature T ₂ in the desorption step may be 200 ° C. or less, or 100 ° C. or less from the viewpoint of energy saving. It may be 50 degrees C or less. The temperature difference (T ₂ −T ₁ ) may be 10 ° C. or higher, 20 ° C. or higher, or 30 ° C. or higher from the viewpoint of easy desorption of carbon dioxide adsorbed on the adsorbent. Good. Temperature _{T 2} of the adsorbent in the desorption step, for example, may be 40 to 300 ° C., may be 50 to 200 ° C., may be 80 to 120 ° C..

In the method using the pressure dependency of the adsorption amount, the CO ₂ adsorption amount increases as the total pressure of the atmosphere in which the adsorbent exists (for example, the total pressure in the container containing the adsorbent) increases. It is preferable to change so that the total pressure in the desorption process is lower than the total pressure. The total pressure may be adjusted by pressurizing or depressurizing, and pressurization and depressurization may be used in combination. As a method for adjusting the total pressure, for example, a method similar to the adsorption step described above can be used. The total pressure in the desorption process may be the ambient atmospheric pressure (for example, 1 atmosphere) or less than 1 atmosphere from the viewpoint of increasing the amount of CO ₂ desorption.

The carbon dioxide desorbed and recovered by the desorption process may be discharged to the outside as it is, but may be reused in the field using carbon dioxide. For example, in greenhouse cultivation for house or the like, since the plant growth by increasing the CO ₂ concentration is accelerated, because they may increase the CO ₂ concentration 1000ppm level, the recovered carbon dioxide, the CO ₂ concentration May be reused to enhance.

When SOx, NOx, dust, or the like is adsorbed on the adsorbent, the CO ₂ adsorptivity of the adsorbent in the adsorption process may be lowered. Therefore, it is preferable that the processing target gas does not contain SOx, NOx, dust, or the like. When the gas to be treated contains SOx, NOx, dust, or the like (for example, when the gas to be treated is exhaust gas discharged from a coal-fired power plant or the like), the carbon dioxide removal method according to this embodiment uses adsorption. From the viewpoint of easily maintaining the CO ₂ adsorptivity of the agent, it is preferable to further include an impurity removal step of removing impurities such as SOx, NOx, and dust from the gas to be treated before the adsorption step. In the impurity removing step, the impurities adsorbed on the adsorbent can be removed by heating the adsorbent. The impurity removal step can be performed using a removal device such as a denitration device, a desulfurization device, or a dust removal device, and the gas to be treated can be brought into contact with the adsorbent on the downstream side of these devices. .

  The adsorbent after the desorption process can be used again in the adsorption process. In the carbon dioxide removal method according to this embodiment, the adsorption step and the desorption step may be repeatedly performed after the desorption step. When the adsorbent is heated in the desorption step, the adsorbent may be cooled by the above-described method and used in the adsorption step. The adsorbent may be cooled by bringing a gas containing carbon dioxide (for example, a treatment target gas containing carbon dioxide) into contact with the adsorbent.

The carbon dioxide removal method according to the present embodiment can be preferably carried out in a sealed space where the CO ₂ concentration needs to be managed. Examples of the space in which the CO ₂ concentration needs to be managed include a building, a vehicle, an automobile, a space station, a submersible, a food or chemical production plant, and the like. The carbon dioxide removal method according to this embodiment can be preferably carried out particularly in a space where the CO ₂ concentration is limited to 5000 ppm or less (for example, a space where the density of people such as buildings and vehicles is high). In addition, since carbon dioxide may adversely affect the production of food or chemical products, the carbon dioxide removal method according to the present embodiment is preferably implemented in a food or chemical production plant or the like. Can do.

<Air conditioning equipment and air conditioning system>
The air conditioner according to the present embodiment is an air conditioner used in an air conditioning target space including a processing target gas containing carbon dioxide. The air conditioner according to the present embodiment includes a flow path connected to the air conditioning target space, and a removal unit (carbon dioxide removal unit) that removes carbon dioxide contained in the processing target gas is disposed in the flow path. In the air conditioner according to the present embodiment, the adsorbent according to the present embodiment is disposed in the removal unit, and the adsorbent comes into contact with the processing target gas and carbon dioxide is adsorbed by the adsorbent. According to the present embodiment, there is provided an air conditioning method including an adsorption process in which a processing target gas in an air conditioning target space is brought into contact with an adsorbent to adsorb carbon dioxide to the adsorbent. The details of the processing target gas containing carbon dioxide are the same as the processing target gas in the carbon dioxide removal method described above. Hereinafter, an example of the air conditioner will be described with reference to FIG.

  As shown in FIG. 1, an air conditioner 100 according to this embodiment includes a flow path 10, an exhaust fan (exhaust unit) 20, a concentration measuring device (concentration measuring unit) 30, and an electric furnace (temperature control unit) 40. And a compressor (pressure control means) 50 and a control device (control unit) 60.

  The flow path 10 is connected to the air conditioning target space R including the processing target gas (indoor gas) containing carbon dioxide. The flow path 10 includes a flow path section 10a, a flow path section 10b, a removal section (flow path section, carbon dioxide removal section) 10c, a flow path section 10d, a flow path section (circulation flow path) 10e, The removal part 10c is arrange | positioned at the flow path 10 with the path part (exhaust flow path) 10f. In the flow path 10, a valve 70 a that adjusts the presence or absence of the inflow of the processing target gas in the removing unit 10 c and a valve 70 b that adjusts the flow direction of the processing target gas are arranged.

  The upstream end of the flow path part 10a is connected to the air conditioning target space R, and the downstream end of the flow path part 10a is connected to the upstream end of the flow path part 10b via the valve 70a. The upstream end of the removal part 10c is connected to the downstream end of the flow path part 10b. The downstream end of the removal part 10c is connected to the upstream end of the flow path part 10d. A downstream side of the flow path portion 10d in the flow path 10 is branched into a flow path section 10e and a flow path section 10f. The downstream end of the flow path portion 10d is connected to the upstream end of the flow path portion 10e and the upstream end of the flow path portion 10f via the valve 70b. The downstream end of the flow path part 10e is connected to the air conditioning target space R. The downstream end of the flow path portion 10f is connected to the outside air.

  An adsorbent 80 that is an adsorbent according to the present embodiment is disposed in the removing unit 10c. The adsorbent 80 is filled in the central portion of the removal portion 10c. Two spaces are formed in the removal unit 10c via the adsorbent 80. The removal unit 10c includes an upstream space S1, a central portion S2 filled with the adsorbent 80, and a downstream space S3. And have. The space S1 is connected to the air conditioning target space R via the flow path portions 10a and 10b and the valve 70a, and the processing target gas containing carbon dioxide is supplied from the air conditioning target space R to the space S1 of the removal unit 10c. . The processing target gas supplied to the removing unit 10c moves from the space S1 to the space S3 via the central part S2, and is then discharged from the removing unit 10c.

  At least part of the carbon dioxide is removed from the processing target gas discharged from the air conditioning target space R in the removing unit 10c. The processing target gas from which carbon dioxide has been removed may be returned to the air conditioning target space R by adjusting the valve 70b or may be discharged to the outside air outside the air conditioning apparatus 100. For example, the processing target gas discharged from the air conditioning target space R passes from upstream to downstream through the flow path part 10a, the flow path part 10b, the removal part 10c, the flow path part 10d, and the flow path part 10e. Can flow into R. Further, the processing target gas discharged from the air conditioning target space R is discharged from the upstream to the downstream via the flow path part 10a, the flow path part 10b, the removal part 10c, the flow path part 10d, and the flow path part 10f. May be.

  The exhaust fan 20 is disposed at the discharge position of the processing target gas in the air conditioning target space R. The exhaust fan 20 discharges the processing target gas from the air conditioning target space R and supplies it to the removing unit 10c.

  The concentration measuring device 30 measures the carbon dioxide concentration in the air conditioning target space R. The concentration measuring device 30 is disposed in the air conditioning target space R.

  The electric furnace 40 is disposed outside the removing unit 10c of the air conditioner 100, and can raise the temperature of the adsorbent 80. The compressor 50 is connected to the removing unit 10c of the air conditioner 100, and can adjust the pressure in the removing unit 10c.

  The control device 60 can control the operation of the air conditioner 100. For example, based on the carbon dioxide concentration measured by the concentration measuring device 30, the control device 60 controls the presence or absence of inflow of the processing target gas in the removal unit 10c. be able to. Specifically, when the concentration measuring device 30 detects that the carbon dioxide concentration in the air conditioning target space R has increased and reached a predetermined concentration due to exhalation or the like, concentration information is sent from the concentration measuring device 30 to the control device 60. Sent. The control device 60 that has received the concentration information opens the valve 70a and adjusts the gas discharged from the removal unit 10c so as to flow into the air-conditioning target space R through the flow channel unit 10d and the flow channel unit 10e. And the control apparatus 60 operates the exhaust fan 20, and supplies process target gas from the air-conditioning object space R to the removal part 10c. Furthermore, the control device 60 operates the electric furnace 40 and / or the compressor 50 as necessary to adjust the temperature of the adsorbent 80, the pressure in the removal unit 10c, and the like.

  When the processing target gas supplied to the removing unit 10c moves from the space S1 to the space S3 via the central portion S2, the processing target gas comes into contact with the adsorbent 80, and carbon dioxide in the processing target gas is absorbed into the adsorbent 80. Adsorb to. Thereby, carbon dioxide is removed from the gas to be treated. In this case, the gas from which carbon dioxide has been removed is supplied to the air-conditioning target space R through the flow path part 10d and the flow path part 10e.

  The carbon dioxide adsorbed on the adsorbent 80 may be recovered in a state of being adsorbed on the adsorbent 80 without being desorbed from the adsorbent 80, or may be recovered after being desorbed from the adsorbent 80. In the desorption process, the electric furnace 40 and / or the compressor 50 are operated to adjust the temperature of the adsorbent 80, the pressure in the removal unit 10c, etc. Carbon dioxide can be desorbed from 80. In this case, for example, the valve 70b is adjusted so that the gas discharged from the removing unit 10c (the gas containing the desorbed carbon dioxide) is discharged to the outside air through the flow path unit 10f. Thus, the discharged carbon dioxide can be recovered.

  The air conditioning system according to the present embodiment includes a plurality of air conditioning apparatuses according to the present embodiment. The air conditioning system which concerns on this embodiment may be provided with the control part which controls the air conditioning driving | operation of several air conditioner. For example, the air conditioning system according to the present embodiment comprehensively controls the air conditioning operation of a plurality of air conditioners.

  For example, as shown in FIG. 2, the air conditioning system 1 according to the present embodiment includes a first air conditioner 100a, a second air conditioner 100b, and a control device (control unit) 62. The control device 62 controls the air conditioning operation of the first air conditioner 100a and the second air conditioner 100b by controlling the above-described control device 60 in the first air conditioner 100a and the second air conditioner 100b. For example, the control device 62 may adjust the air conditioning operations of the first air conditioner 100a and the second air conditioner 100b under the same conditions, and the first air conditioner 100a and the second air conditioner 100b. You may adjust so that air-conditioning operation may be performed on different conditions. The control device 62 can transmit information regarding the presence / absence of inflow of the processing target gas in the removal unit 10c to the control device 60.

  The air conditioner and the air conditioning system are not limited to the above-described embodiment, and may be appropriately changed without departing from the spirit thereof. For example, the adsorbent only needs to be disposed in the removal portion, and may be disposed in a part of the inner wall surface without being filled in the central portion of the removal portion. The control content of the control unit of the air conditioner is not limited to controlling the presence or absence of inflow of the processing target gas in the removal unit, and the control unit may adjust the inflow amount of the processing target gas in the removal unit.

  In the air conditioner, the gas to be processed may be supplied to the carbon dioxide removing unit using a blower instead of the exhaust fan, and when the gas to be processed is supplied to the carbon dioxide removing unit by natural convection, an exhaust means is provided. It may not be used. Further, the temperature control means and the pressure control means are not limited to the electric furnace and the compressor, and various means described above can be used in the adsorption process and the desorption process. The temperature control means is not limited to the heating means, and may be a cooling means.

  In the air conditioner, each of the air-conditioning target space, the carbon dioxide removal unit, the exhaust unit, the temperature control unit, the pressure control unit, the concentration measurement unit, the control device, etc. is not limited to one, and a plurality of them may be arranged. Good. The air conditioner includes a humidity controller for adjusting the dew point and relative humidity of the gas to be treated; a humidity measuring device for measuring the humidity of the air conditioning target space; a removal device such as a denitration device, a desulfurization device, and a dust removal device May be.

  EXAMPLES Hereinafter, although the content of this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to a following example.

<Preparation of adsorbent>
Example 1
After mixing 100 parts by mass of cerium oxalate powder and a solution containing 130 parts by mass of ammonia and 180 parts by mass of hydrogen peroxide, the mixture was stirred to produce a brown precipitate. The liquid containing the precipitate was filtered to collect the precipitate, and then the precipitate was washed. The precipitate was confirmed to be ceria by XRD measurement.

  The precipitate was then heated at 80 ° C. for 1 hour using a hot water bath. Foaming was confirmed from the precipitate during heating, and foaming was completed after the heating for 1 hour. The precipitate after heating turned yellow.

  Next, the precipitate was added to a nitric acid solution, and then ultrasonic waves were applied for 5 hours to disperse the precipitate, thereby obtaining a yellow transparent solution. As the nitric acid solution, a solution obtained by diluting 16 mL of a 60% by mass nitric acid solution with 200 mL of purified water was used.

  Next, the mixture was stirred after adding aqueous ammonia, and re-aggregated to produce a yellowish white precipitate. As the ammonia water, a solution obtained by diluting 20 mL of 28 mass% ammonia water with 180 mL of purified water was used.

  Next, a liquid containing a yellowish white precipitate was filtered to collect the precipitate, and then the precipitate was washed. Then, yellowish white powder (adsorbent) was obtained by drying at 120 degreeC for 1 hour.

(Example 2)
A yellowish white powder (adsorbent) was obtained in the same manner as in Example 1 except that the brown precipitate was added to the nitric acid solution without heating at 80 ° C. When sonicated in nitric acid solution, a clear and colorless solution was formed. After that, when ammonia water was added, discoloration further progressed after a blue-violet precipitate was formed, and finally a yellowish white precipitate was formed.

(Comparative Example 1)
According to the following procedure, 15 g of cerium hydroxide (Ce (OH) ₄ ) was calcined in air. First, after raising the temperature to 120 ° C. at 5 ° C./min in an electric furnace, the temperature was maintained at 120 ° C. for 1 hour. Then, after heating up to 300 degreeC at 5 degree-C / min, temperature was hold | maintained at 300 degreeC for 1 hour. Thereby, a yellowish white powder (adsorbent) was obtained.

<Measurement of specific surface area>
First, as pretreatment, the adsorbents of Examples 1 and 2 were heated at 200 ° C. while evacuating. Subsequently, after measuring an adsorption isotherm of nitrogen at −196 ° C., a BET specific surface area was measured using a BET (Brunauer-Emmett-Teller) method. The specific surface area of the adsorbent of Example 1 was 182 m ² / g, and the specific surface area of the adsorbent of Example 2 was 158 m ² / g.

<Measurement of carbon dioxide adsorption>
First, the adsorbent was pelletized at 200 kgf by a press using a mold having a diameter of 40 mm. Next, the pellets were crushed and then sized into granules (particle size: 0.5 to 1.0 mm) using a sieve. Thereafter, 1.0 mL of the adsorbent was measured using a graduated cylinder and fixed in a reaction tube made of quartz glass.

  Next, as a pretreatment, the temperature of the adsorbent was raised to 200 ° C. using an electric furnace while flowing helium (He) through the reaction tube at 150 mL / min, and then held at 200 ° C. for 1 hour. Thereby, impurities and gas adsorbed on the adsorbent were removed.

Next, after cooling the adsorbent to 50 ° C., the CO ₂ adsorption amount was measured by a CO ₂ pulse adsorption test while maintaining the adsorbent temperature at 50 ° C. in an electric furnace. Specifically, the CO ₂ pulse adsorption test was performed by the following method. The CO ₂ adsorption amount was 24.2 g / L (Example 1), 14.124 g / L (Example 2), and 4.2 g / L (Comparative Example 1).

[CO ₂ pulse adsorption test]
As a sample gas, 10 mL of a mixed gas (relative humidity: 0%) containing 12% by volume of CO ₂ and 88% by volume of He was used. The sample gas was introduced in a pulsed manner every 4 minutes for 2 minutes. At this time, the total pressure in the reaction tube was adjusted to 1 atmosphere. Next, the CO ₂ concentration at the outlet of the reaction tube was measured by a gas chromatograph (carrier gas: He). The introduction of the sample gas was continued until the CO ₂ concentration measured at the outlet of the reaction tube was saturated. CO ₂ concentration is the amount of carbon dioxide adsorbed in until saturated (unit: g) of the CO ₂ adsorption amount (unit: g / L) was determined.

  DESCRIPTION OF SYMBOLS 1 ... Air conditioning system, 10 ... Channel, 10a, 10b, 10d, 10e, 10f ... Channel part, 10c ... Removal part, 20 ... Exhaust fan, 30 ... Concentration measuring device (concentration measuring part), 40 ... Electric furnace, 50 ... Compressor, 60, 62 ... Control device (control unit), 70a, 70b ... Valve, 80 ... Adsorbent, 100, 100a, 100b ... Air conditioner, R ... Air-conditioning target space, S1, S3 ... Space, S2 ... Center Department.

Claims (13)

A method for producing an adsorbent used for removing carbon dioxide from a gas to be treated containing carbon dioxide,
A first step of reacting a cerium salt, hydrogen peroxide and ammonia to obtain a first product;
A second step of reacting the first product with an acid component to obtain a second product;
And a third step of reacting the second product with the base component.   The method for producing an adsorbent according to claim 1, wherein the cerium salt includes at least one selected from the group consisting of cerium oxalate and cerium nitrate.   The method for producing an adsorbent according to claim 1, wherein the acid component includes nitric acid.   The manufacturing method of the adsorption agent as described in any one of Claims 1-3 with which the said base component contains ammonia.   The method for producing an adsorbent according to any one of claims 1 to 4, further comprising a heating step of heating the first product between the first step and the second step.   The manufacturing method of the adsorption agent of Claim 5 whose heating temperature of the said heating process is 70 degreeC or more.   The adsorbent obtained by the manufacturing method of the adsorbent as described in any one of Claims 1-6.   The adsorbent obtained by the method for producing an adsorbent according to any one of claims 1 to 6, or the adsorbent according to claim 7 is brought into contact with a treatment target gas containing carbon dioxide to produce carbon dioxide. A method for removing carbon dioxide, comprising the step of adsorbing the adsorbent on the adsorbent.   The method for removing carbon dioxide according to claim 8, wherein the carbon dioxide concentration of the gas to be treated is 5000 ppm or less.   The method for removing carbon dioxide according to claim 8, wherein the concentration of carbon dioxide in the gas to be treated is 1000 ppm or less. An air conditioner used in an air conditioning target space containing a processing target gas containing carbon dioxide,
A flow path connected to the air-conditioned space,
A removal section for removing carbon dioxide contained in the processing target gas is disposed in the flow path,
The adsorbent obtained by the method for producing an adsorbent according to any one of claims 1 to 6, or the adsorbent according to claim 7 is arranged in the removal section,
An air conditioner in which the adsorbent comes into contact with the gas to be treated and the carbon dioxide is adsorbed on the adsorbent.   The air conditioner of Claim 11 whose carbon dioxide concentration of the said process target gas is 5000 ppm or less.   The air conditioning apparatus according to claim 11, wherein the carbon dioxide concentration of the processing target gas is 1000 ppm or less.

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